Safety and Efficacy of Post-Eradication Smallpox Vaccine as an Mpox Vaccine: A Systematic Review with Meta-Analysis

Abstract

According to the World Health Organization, 83,339 laboratory-confirmed cases, including 72 deaths, of mpox (formerly known as monkeypox), have been reported from 110 locations globally as of 20 December 2022, making the disease a public health concern. Most of the cases (56,171, 67.4%) were reported from countries in North America. Limited data on vaccine effectiveness in the current mpox outbreak are available. However, the modified vaccinia virus (smallpox vaccine) has been predicted to prevent or reduce the severity of the mpox infection. The present study of systematic review and meta-analysis aimed to evaluate the modified vaccinia vaccine’s safety and efficacy on mpox by using reported randomized clinical trials. Following guidelines from the Cochrane Collaboration and PRISMA, multiple databases including PubMed, PLOS ONE, Google Scholar, British Medical Journal, and the U. S. National Library of Medicine were searched. Out of 13,294 research articles initially identified, 187 were screened after removing duplicates. Following the inclusion and exclusion criteria, the meta-analysis included ten studies with 7430 patients. Three researchers independently assessed the risk of bias in the included study. The pooled results suggest that the vaccinia-exposed group had fewer side effects when compared to the vaccinia naïve group (odds ratio: 1.66; 95% CI: 1.07–2.57; p = 0.03). Overall, the modified vaccinia has proven safe and effective in both vaccinia naïve and previously exposed groups, with higher efficacy in the previously exposed groups.

Immunogenicity and Safety of Modified Vaccinia Ankara (MVA) Vaccine—A Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…A recent meta-analysis evaluated the safety of MVA among vaccinia-naïve versus vaccinia-experienced people and demonstrated higher rates of adverse events in the former [ 37 ]. The prescribing information for MVA (JYNNEOS) summarizes data from 22 studies (7859 individuals) and reports some variability in AEs between vaccine-experienced and naïve individuals, along with similar rates of AEs between healthy individuals and those with HIV or atopic dermatitis [ 38 ].…”

Mpox: Clinical Outcomes and Impact of Vaccination in People with and without HIV: A Population-Wide Study

“…Although the efficacy of the vaccine against mpox has not been assessed in clinical trials, real-world studies have shown good effectiveness [13,14,20,21]. A recent study from Israel evaluating 1037 male individuals who completed only the first subcutaneous dose of the vaccine and were followed up for at least 90 days estimated that the adjusted vaccine effectiveness in preventing infection was 86% (95% confidence interval 59-95%) [22].…”

“…The earlier vaccinia virus vaccination administered against smallpox provided crossimmunity to the mpox virus as both viruses are closely related to Orthopoxviruses [13,14]. Discontinuation of routine smallpox vaccination following smallpox eradication in the early 1980s and thus waning immunity with no immunity coverage in the population <40 years of age has probably been an important risk factor for the current emergence of mpox as a public health thread [9].…”

Knowledge and Attitude of Human Monkeypox Viral Infection Among Healthcare Practitioners and Students in Saudi Arabia: A Cross-Sectional Study

“…In the current study, a total of 212 participants were included out of 219, and the majority of participants provided correct responses about the type of microorganisms that cause human Mpox infection, which is a virus, these results were comparable to a previous study that was conducted in Indonesia. This study aimed to determine general practitioners' knowledge regarding Mpox, and majority of participants (96.6%) knew Mpox is a virus [ 14 ]. In the current study, majority of participants were aware of the low prevalence of Mpox in Saudi Arabia, but only small proportion identified the correct number of cases in Saudi Arabia.…”